The invention relates to a pointer instrument, especially for a vehicle, having a disk pointer which can be illuminated by a light source, the disk pointer being designed in particular like a circle or circular ring and being connected to a flexible lead.
Such a pointer instrument, in which the disk pointer is designed such that it can be pivoted about an immovable pointer axis, and in which the pointer flag is applied as a mark on the disk pointer, is increasingly used nowadays, above all in the vehicle industry, and thus belongs to the prior art.
In such a pointer instrument, the pointer axis is connected to the pointer instrument such that it cannot rotate and has a comparatively large diameter, so that, for example, a further display designed as a liquid-crystal display can be fitted to a front face of the disk pointer, at the center of the pointer instrument, so that it can easily be read by an observer.
Furthermore, embodiments of such a pointer instrument are known in which the disk pointer, which may be annular, for example, is mounted at its periphery, and therefore even the central pointer axis is dispensed with.
While in the case of conventional pointer instruments having a pointer shaft deflecting a pointer flag, the flexible lead is led spirally around the pointer shaft and, as a result, is wound up or unwound by the latter as the pointer is deflected, this can be implemented only to an inadequate extent in one of the above embodiments.
In this case, in the case of a lead which is laid at the periphery of the disk pointer, it proves to be disadvantageous that a large difference in length of the lead has to be compensated for during the deflection of the disk pointer. At the same time, the transmission of restoring forces from the lead to the disk pointer must be ruled out, so that additional measures, such as a multiple spiral winding, must be provided. As a result, both the space requirement and the outlay on production are relatively high.
In an embodiment in which the lead is laid essentially freely through the space between the disk pointer and the components located underneath, by contrast it proves to be disadvantageous that jamming or damage can easily occur during any pivoting movement of the disk pointer.
The invention is based on the problem of configuring a pointer instrument of the type mentioned at the beginning in such a way that the lead can be arranged simply and at the same time protected against damage.
According to the invention, this problem is solved by the lead running at least approximately concentrically curved in relation to the disk pointer and having two legs joined by a 180xc2x0 bend and running at a distance above each other, the first leg resting against a rear of the disk pointer and the second leg being fixed to a rear component of the pointer instrument, with an axial spacing from the disk pointer.
As a result, during the pivoting movement of the disk pointer, the lead is unrolled on the rear of the latter, so that, on the one hand, an exact movement path is predefined without the risk of damage and, on the other hand, the space requirement is very low. As a result of the concentric curvature of the lead, the latter follows the circular path predefined by the pivoting movement of the disk pointer. There is therefore no production of transverse forces in the direction of the center of the disk pointer which could lead to the lead sliding on the rear of the disk pointer. In this case, in particular the central area and the periphery of the disk pointer are not restricted by the course of the lead.
As a result of this, the lead can also be used without problems in the case of a disk pointer which is mounted at its periphery and therefore does not have a central axis or shaft. In this case, the restoring forces produced by the lead as a result of its bending and acting on the disk pointer are low.
Another particularly advantageous embodiment of the invention is also provided when there is arranged on the rear of the disk pointer a ledge, against which the lead rests with one side pointing toward the center of the disk pointer.
This ledge extends at least so as to correspond to the maximum deflection of the disk pointer and therefore prevents the lead slipping toward the center. For this purpose, the ledge can be designed as a stop and, for example, can additionally be provided with an inclined face, which simplifies the action of laying the lead against the rear of the disk pointer and permits its exact guidance.
In this case, a particularly well-suited development of the invention is provided by the disk pointer having a groove which is arranged on its rear and in which the lead rests.
As a result, the lead is optimally protected against damage and, for its part, does not hamper the functioning of the disk pointer. At the same time, this development permits a space-saving implementation in which the lead can be inserted such that it is set back in the groove. For this purpose, the groove can have additional insertion aids, for example inclined faces or chamfers, by which means guiding the lead can be further improved.
A particularly advantageous embodiment of the invention is also provided by the lead being an electric conductor track applied to a film.
As a result, the lead has a thickness which is only very low and at the same time has a high flexibility, which can be pronounced to different extents in different directions. Therefore, the guide elements which are otherwise necessary to maintain an exact movement path can largely be dispensed with. It is also possible, for example, for the conductor track to make direct contact with the light source at one end.
It is also particularly advantageous in this case if the light source is a light-emitting diode inserted into a recess arranged off-center in the disk pointer. This makes an extremely flat design of the disk pointer possible, the light-emitting diode needing to be covered only by a translucent pointer flag. At the same time, the central area of the disk pointer remains free of components and can thus be used in an optimum manner for further displays.
On the other hand, another particularly effective embodiment of the invention is also achieved by the lead being designed as an optical waveguide. By this means, the light from a light source arranged in the rear area of the pointer instrument can be coupled into the optical waveguide and can be coupled out of the front side of the disk pointer. The optical waveguide can also merge in this case into a light output coupling face formed as a pointer flag, so that the number of components needed can be reduced, it being in particular unnecessary to provide any light source on the disk pointer. At the same time, the light source can also emit light into a number of optical waveguides for the purpose of illuminating different displays.
It is also particularly expedient if the rear component is a printed circuit board. As a result, contact can be made directly with the lead, or the lead can be connected to a light source. In this case, for example, a zero-force plug known per se makes assembly easier and, in the event of servicing, permits easy replacement.
Another particularly expedient refinement of the invention is provided by the disk pointer being designed to be essentially transparent and, on its rear, in the area where the lead can be placed on it, having a section with a reduced transmission.
By this means, the lead, which rests against the rear of the disk pointer, in particular during any deflection of the disk pointer, cannot be perceived by an observer. For this purpose, the section can be provided, for example, with a coating or a textured surface.
This section having a reduced transmission is achieved in a particularly advantageous development of the invention by the section being designed as an annular recess and thus being able to be made without trouble in a common machining step with the ledge or groove.